Practical Two: Cellular Pathology

 

Analysis of CA’s biopsy slides.  Examine the image in figure 1 and answer the following questions:

 

 

Figure 1. Haematoxylin and eosin stained image of CA’s biopsy x10 magnification

 

  1. Is CA’s biopsy displaying a normal tissue morphology throughout the section? Circle areas on figure 1 displaying normal morphology (3 marks)

 

 

 

 

 

  1. List the four main layers of the large intestine (1 mark)

 

 

 

 

 

 

  1. Has the gut sample in figure 2 been cut in cross or longitudinal section? (1 mark)

 

Figure 2. H&E-stained image of human gut

 

 

 

 

 

 

 

  1. In a H&E stain of the large intestine which of the following cells nuclei should appear darker, goblet or absorptive cells? (1 mark)

 

 

 

 

 

  1. What histological/cellular features/processes can be seen in A and B, which are also often features seen in other pathologies? (2 marks)

 

Figure 3 H&E stain of human adenocarcinoma

 

A is showing=

 

 

B is showing=

 

 

 

  1. What are for the following definitions describing?

 

“Abnormal cytologic changes in epithelial cells associated with intensely stained nuclei or irregular nuclear chromatin often associated with neoplasia.” (1 mark)

 

 

 

 

 

 

“Rehydrate a section through graded alcohols to 100% H2O” (1 mark)

 

 

 

 

 

  1. The accumulation and nuclear translocation of ß-catenin often occurs in adenocarcinomas. Other than ß -catenin itself, which gene is most often mutated in colonic adenocarcinomas leading to this increase? (1 mark)

 

 

Further tests are performed on CA’s biopsy and an immunhistochemical stain for p53 is performed using horseradish peroxidase as a visualising enzyme and the results from this are shown in figure 4.

 

Figure 4. High power image of CA’s biopsy immunostained for p53 and counterstained with haematoxylin

 

  1. Using a figure (i.e. a diagram with annotated labels) outline the intracellular mechanism regulating p53 levels in cells. Your answer as a minimum should make reference to the following mdm2, PUMA, CHK1/2, proteasome (4 marks).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. Why would an increase in p53 protein level contribute to CA’s disease if p53 is a tumour suppressor? Suggest a reason for this paradox? What may have happened? (3 marks)

 

 

 

 

 

 

 

 

 

 

  1. Detail why molecular analysis of colonic adenocarcinomas may look at BRAF mutations? What other mutations in intracellular signalling components linked to BRAF may be tested for? (2 marks)

 

 

 

 

 

 

 

 

 

  1. Using a figure (i.e. a diagram with annotations) describe the signalling cascade that BRAF forms part of (this should include all elements from receptors on the cell membrane, and the intracellular signalling that transmit the signal to the nucleus) (4 marks)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. Targeted therapies, such as panitumimab are used in some cases of adenocarcinoma of the colon. What DNA based laboratory technique could you use to determine if DS would respond to panitumumab? (1 mark)

 

 

 

 

 

 

 

 

Total Mark=                    /25                      =              %

 

Supporting resources: you may find the following useful as a starting point for further reading (copies of the texts are in the library.)

 

The open science lab on-line virtual microscope gut slides 21-25- choose gut from drop down menu https://learn5.open.ac.uk/mod/htmlactivity/view.php?id=19

 

Lodish, Berk, Kaiser, Bretscher, Ploegh, Amon, Scott (2013) Molecular cell biology, 7th edition, Lodish, Macmillan Higher Education (any other molecular cell biology text in the library would also be of similar use e.g. Alberts, Karp etc.)

 

Weinberg R (2013) The Biology of Cancer. Garland Science Press

 

Henwood A (2010) Microscopic Quality Control of Haematoxylin

and Eosin – Know your Histology. Connection 10: 115-120 available from https://www.researchgate.net/publication/316510040_Connection_2010_115_Microscopic_Quality_Control_of_Haematoxylin_and_Eosin_-_Know_your_Histology

 

Orchard G and Nation B (2012) Histopathology. Oxford University Press

 

Further specific searches for reviews and papers on Pubmed would also help and aid your understanding.